Telephone-amplifier.



J. J. COMER.

TELEPHONE AMPLIFIER.

APPLICATION FILED MAYS. 1912.

1 1 85 87 8 Patented June 6, 1916.

2 SHEETS-SHEET I.

y EMT/V5332 mam/701?.-

' ATTORNEYS,

THE COLUMBIA PLANOGRAPH (70., WASHINGTON, D. C.

1.1. COMER.

TELEPHON AMPLIFIER.

APPLICATION FILED MAYfi. 1912.

1 1 85,878 Patented J une 6, 1916.

2 SHEETSSHYEET 2.

M/ITNESSES' JVVENTO/Ef- TAT s PATENT or re UNITED s E E E.

JOHN J. COMER, OF CHICAGO, ILLINOIS, ASSIGNOR T0 AUTOMATIC ENUNCIATOR COM- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE-AMPLIFIER.

Specification of Letters Patent.

Patented June 6, 1916.

Application filed May 6, 1912. Serial No. 695,334.

To all whom it may concern:

Be it known that I, JOHN J. CoMER, a citizen of the United States of America, and resident of Chicago, Cook county, Illinois, have invented a certain new and useful Improvement in Telephone- Amplifiers, of which the following is a specification.

My invention relates to telephone ampli fiers or repeatersthat is, to instruments which are employed for repeating voice-current impulses.

lVly invention is particularly adapted for instruments for use in transmitting music, and in this connection is used more particularly to increase the number of instruments which are operated by a single master transmitter, rather than increasing the amplitude of the vibrations, such as is the case when the instrument is employed as a repeater. It will be obvious, however, that if desired the instrument could be adjusted so as to operate as a repeater.

In the transmission of music it is important that the instrument be so constructed that all extraneous or foreign vibrations are eliminated. In this connection it is desirable that the microphone transmitter be very fleXiblyconnected with the magnetic receiver and, furthermore, that all metallic connections between the vibrating armature and the parts of the microphone transmitter be eliminated. If this is not done certain metallic and other objectionable sounds are obtained. Furthermore, in order to obtain the most perfect reproduction of musical sounds it is necessary that the vibrating parts be very accurately adjusted and be so constructed that they are capable of vibrating very rapidly, and yet they must be controlled in order that the vibrations received will be accurately transmitted.

The principal objects of my invention are the provision of an amplifier which is so constructed that efficient results are obtained in the manner pointed out above. That is, I provide an amplifier in which the armature is so constructed and mounted that it is very sensitive to the variations of current in the electromagnet of the receiver, but the vibrations of this armature are controlled so as to prevent any false vibrations occurring 1n the same. Furthermore, the mlcrophone part of my amplifier is entirely free from any metallic connection with the vibrating armature and is very flexibly connected with the same.

By the use of my amplifier I am enabled to energize as many as five hundred reproducers from a single master transmitter.

The features and objects of my invention Wlll be more readily understood by reference to the accompanying drawings, in which Figure 1 is a side View of an amplifier embodying the features of my invention. Fig. 2 is a top view of the same. Fig. 3 is an end view. Fig. 4 is an end view taken on the line H of Fig. 2, with the microphones and mounting plates removed. Fig. 5 is a sectional view taken on line 5-5 of Fig. 2. Fig. 6 is a sectional view taken on line 6-6 of Fig. 2.

Throughout the drawings similar reference characters refer to similar parts.

I have illustrated an amplifier comprising a U-shaped magnet 7 having pole-pieces 8 and 9. On the pole-piece 9 is mounted an electromagnet coil 10. A pair of non-magnetic supporting arms or brackets 11 and 12 are mounted on the forward ends of these pole-pieces, and these supporting arms are joined together by a pair of non-magnetic cross-bars 13 and 14. Mounted on each of these cross-bars 13 and 14 there is a pair of threaded supporting posts 15 and 16 upon the upper ends of which are mounted the flat springs 17 and 18. These flat springs extend beneath and are secured to the aluminum bar 19 which supports the armature 20. This armature is preferably rectangular in shape and is supported adjacent to the two pole-pieces 8 and 9, thereby forming a double air gap in the magnetic circuit. The use of this double air gap produces a much more sensitive armature and one which will respond more readily to the rapid changes of current in the coil 10.

Mounted upon the end of the supporting arms 11 and 12 there is a supporting plate 21. The base plate 22 is mounted adjacent to the supporting plate 21 and is separated therefrom by the felt packing 23. These two plates are preferably recessed as shown, whereby this felt packing is more readily held in place. Mounted on the base plate 22 is a pair of microphones each comprising stationary electrodes 21 and E25 and a movable electrode 26. These movable electrodes are carried by stems 2? which pass through the plates 21 and and are secured to opposite ends of the aluminum bar 19. These rods 27 do not contact with the plates 21 and 22 and are insulated from the bar 19 by means of the rubber washers 2S and the felt packing 29. These stationary electrodes 2i and 25 are separated by the insulating rings 30 which form the carbon receptacle 31 within which is located the granular carbon. These rings 30 are separated by means of washers 3Q surrounding the tiebolts 34:. The space btween these rings is then packed with asbestos. This asbestos likewise surrounds the stems 27 and also the periphery of the movable electrode 26. Upon the opposite sides of each of these microphones there is mounted a non-mag netic supporting plate and the various parts of the microphone transmitter are all held together by the tie-bolts 3%. The base plate 22 and the plate 21 are connected together by means of the tie-bolts 3%, which tie-bolts are thoroughly insulated from the base plate 22 by means of the felt packing 36 which surrounds each of the tie-bolts and sets within recesses in this base plate, as clearly shown in Fig. 2. Passing through the central portion of the plate 21 there is a threaded stud 37 which is provided with an enlarged end portion 38 which bears against a felt disk 39 set wi hin the recessed portion of the bar 19.

By means of the construction described the armature is properly adjusted with respect to the pole-pieces, and when so adjusted the springs 17 and 18 are preferably slightly bowed downward. The tension of these springs is sulhcient to prevent the armature coming in contact with the polepieces when attracted to the same, and the vibrations of this armature are controlled and dampened by means of a felt disk 59 bearing againstthe enlarged end portion 38 of the stud 3'7. It will further be noticed that the entire weight of this armature and the supporting parts are carried by the lower part of the supporting arms 11 and 19. I find that this gives much better results than when this armature is supported from above by means of the plate 21, as in the latter instance the vibrations of the armature are apt to set up foreign vibrations in this plate which would be more apt to be transmitted to the microphones than in the present construction, in which very few of these foreign vibrations are set up in this plate 21.

In the operation, the vibrations of the armature are transmitted through the bar 19 to the rods 27 and thus operate the movable electrodes of the microphones in a manner which will be readily understood. This vibration of the armature would tend to set up foreign or extraneous vibrations in the frame of the magnet, and this would be transmitted through the supporting arms 11 and 12' to the plate 21. By the use of the felt packing 23 located between this plate 21 and the supporting plate 92, however, I prevent any of these extraneous vibrations from being transmitted to the microphone. This felt packing is preferably quite loose, so that a very flexible construction is obtained, but by having these plates recessed in the manner shown and described the parts are firmly held in position. It will, of course, be understood that in place of felt I could employ other insulating material, such as rubber or leather, but I find that the best results are obtained by the use of felt. By this construction, therefore, it will be seen that I provide an armature which is very sensitive and which responds readily to the slight changes in current in the magnet coil, and, furthermore, by having all parts insulated all extraneous vibrations are prevented from affecting the microphones. I thus obtain very eflicient transmission and one which is particularly zulvantageous in the transmission of musical sounds.

While I have illustrated one particular embodiment of my invention, it will be understood that I do not wish to be limited to the exact construction shown and described.

What I claim as my invention is 1. In a telephone amplifier, an electro magnet, an armature therefor, a member directly supporting said armature, a rod connected at one end to said member and insulated from all metallic contact therewith, and a microphone transmitter having a movable electrode connected directly to the opposite end of said rod.

2. In a telephone amplifier, a magnet, an armature therefor, a supporting member for said armature, rods connected to the opposite ends of said supporting member and insulated therefrom, and microphone transmitters having independent movable elec trodes connected to the opposite ends of said rods.

3. In a telephone amplifier, an electromagnet, an armature therefor, a supporting plate carried by said magnet, a base plate mounted adjacent to but insulated from said supporting plate, a microphone transmitter mounted on said base plate, and a connecting rod connected at one end to an electrode of said transmitter and at its opposite end connected to but insulated from said armature.

4. In a telephone amplifier, an electromagnet, an armature therefor, a supporting plate carried by said magnet, a base plate mounted adjacent to said supporting plate, a felt disk separating said plates, a microphone transmitter mounted upon said base plate and having a movable electrode, and connections from said movable electrode to said armature.

5. In a telephone amplifier, an electromagnet, an armature therefor, a supporting member for said armature, a supporting plate carried by said magnet, a base plate mounted adjacent to said supporting plate, a felt disk located between said plates, a pair of microphone transmitters each having a movable electrode mounted upon said base plate, and connections from said movable electrodes to opposite ends of said supportin g member.

6. In a telephone amplifier, an electromagnct, an armature therefor, a supporting member for said armature, a supporting plate carried by said magnet, a base plate mounted adjacent to said supporting plate, a felt disk located betvveen said plates, a pair of microphone transmitters each having a movable electrode mounted upon said base plate, and connections from said movable electrodes to opposite ends of said supporting member, said connections being insulated from said supporting member.

7. In a telephone amplifier, an electromagnet, a pair of non-magnetic supporting arms mounted upon the pole-pieces of said magnet, a supporting member carried by said arms, an armature mounted upon said supporting member, a supporting plate mounted upon said arms, a base plate mounted adjacent to said supporting plate and insulated therefrom, a microphone transmitter mounted upon said base plate, and connections from said transmitter to said armature.

8. In a telephone amplifier, an electromagnet, a pair of nonmagnetic supporting arms mounted upon the pole-pieces of said magnet, a supporting member carried by said arms, an armature mounted upon said supporting member, a supporting plate mounted upon said arms, a base plate mounted adjacent to said supporting plate and insulated therefrom, a pair of microphone transmitters having movable electrodes, and connecting rods connected to said movable electrodes and connected to but insulated from said supporting member.

9. In a telephone amplifier, a U-shaped electromagnet, a pair of supporting arms carried by said magnet, a supporting plate carried by said arms and extending across the. end of said magnet, an armature for said magnet, and means carried by said plate for damping the vibrations of said armature.

10. In a telephone amplifier, a magnet, non-magnetic supporting arms carried by said magnet, an armature carried by said supporting arms, and a soft pad mounted adjacent to said armature for damping the vibrations of said armature.

11.. In a telephone amplifier, a magnet, a pair of non-magnetic supporting arms carried by said magnet, a pair of flat springs carried by said supporting arms, a supporting member carried by said springs, and an armature mounted upon said supporting member.

12. In a telephone amplifier, an electromagnet, a pair of supporting arms carried thereby, a pair of flat springs adjustably carried by said supporting arms, a supporting member mounted transversely on said springs, an armature carried by said mem her, and means located adjacent to said armature for damping the vibrations of the same.

13. In a telephone amplifier, a magnet, a pair of supporting arms, a pair of springs carried by said supporting arms, an armature carried by said springs, a supporting plate mounted on said supporting arms, and an adjustable member carried by said plate for damping the vibrations of said armature.

14. In a telephone amplifier, a pair of supporting arms, a pair of flat springs adjustably carried by said supporting arms, a sup porting member carried by said springs, an armature mounted upon said member, a supporting plate mounted on said supporting arms, a base plate mounted adjacent to said supporting plate but insulated therefrom, a microphone transmitter mounted upon said base plate, and connections from the movable electrode of said transmitter to said supporting member.

15, In a telephone amplifier, a pair of supporting arms, a pair of fiat springs adjustably carried by said supporting arms, a supporting member carried by said springs, an armature mounted upon said member, a supporting plate mounted on said supporting arms, a base plate mounted adjacent to said supporting plate but insulated therefrom, a

of said armature for damping the vibrations of the same, a microphone transmitter, and a rod connected directly to said transmitter and extending to said armature.

17. In a teieohone amplifier, an electroinagnet, an armature therefor providing a magnetic circuit open at two points, a pair of bowed springs for supporting said arn1atnre, means for damping the vibrations of said armature, a microphone transmitter, 10 and connections from said armature to Said transmitter.

Signed by me at Chicago, Cook county, Illinois, this 3rd day of May, 1912.

JOHN J. COMER. Witnesses:

H. A. Swnxanrox, S. LEWIS.

hopies of this patent may be obtained for five cents each, by addressing the Commissioner 01' Patents. Washington, 1). 0. 

